Means for obtaining and controlling fluid pressure



E. G. STAUDE Aug. s, 1939.

IEANS FOR- OvBTAINING AND CONTROLLING FLUID'BESSUARE Filed Oct'. 16, 1937 4 Sheets-Sheet 2 UNMNN Om.

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E. G. STAUDE InANs- Fon oBrAINING AND coN'rRoLLING FLUxD PRESSURE Filed Oct. 16, 1937 4 Sheets-Sheet 3 TTC/2HE Y E. G. STAUDE Aug. s, 1939.

B'IEANS 'FOR OBTAINIG AND CONTROLLING FLUID PRESSURE l Filed oct. 1s, 1937 4 sheets-sheet 4 v .mum wv .O` mm WM. a 0N w KN Om, U Vl mv vv bmrmv Nm Q m E Nm m 5 n n E mw E s m m l w H mm. wm mm .vm Y n E. ww ffl/O a Q Q NN Q mm Q Patented Aug. 8, 1939 PATENT OFFICE MEANS FOR OBTAININ G AND CONTROLLING FLUID PRESSURE Edwin G. Stande, Minneapolis, Minn., assigner of one-half to Olive Minn.

Bertha Stande, Minneapolis,

Application October 16, 1937, Serial No. 169,501

6 Claims.

This invention relates to a method and means for obtaining differential fluid pressure action, and nds valuable application as a iluid pressure actuator for hydraulic brakes. It will be understood, however, that although the specific combination of the device, with a hydraulic braking system is claimed per se, yet thel principle of operation as a method or as a means, has a much Wider application in the eld of fluid pressur producing and controlling devices.

In conventional automobile trucks, buses, etc., it is customary to provide a single cylinder having a piston, operable either manually or by power, for creating pressure in the uid system of hydraulic brakes to overcome the tension of the retractor springs and take up the clearances between the brake shoes and brake drums and to apply the brakes.

In order to create suflicient volume of piston displacement when the power is applied manually through a foot pedal traveling, for example, about four inches, the cylinder and piston have to be of such size that the required fluid pressures of eight hundred to one thousand pounds cannot be obtained without excessive manual pressure on the foot pedal. l 1t is wen understood that at the beginning of pedal motion or stroke very littlel pressure is required, because then it is more aquestion of quick volume than ol' high pressure, to merely overcome the resistance of the retractor springs-on the brake shoes and move the shoes into contact with the brake drum.

It is therefore the object of my invention to provide a mechanism that will create quick volume and fast piston motion at the beginning of the stroke of the fluid displacing device in respect to travel, and then when actual braking performance is required, to accomplish this with a much smaller piston area in orderV to reduce pedal pressure, or with other power application in addition to the pedal, since after the slack is once taken up very little additional stroke movement is required, since it is then largely a matter only of applying additional pressure. This device may 45 be used for purposes other than applying brakes on motor cars, trucks, buses or railway cars, etc.,

. because it may easily be applied to clutches or other vehicle controls or may even be applied to operate remote controls on industrial machinery.

Features include: the arrangement of the cylinders; the means by which they are interconnectedgthe specific' structures for controlling the movements'ho'Ptranslatable elements, like pistons, for any purpose; the vmethod oi controlling the 55 pistons yto operate both and then 4discontinue the (Cl. so-54.6)

operation of one while continuing operation of the other; the use of the method and apparatus in conjunction with ahydraulic brake; the method irrespective of its specic use; and all details of construction and mechanical movements, along with the broader ideas of means inherent in the disclosure.

Features and advantages will appear in the description of the drawings forming a part of this application, and in said drawings,

Figure 1 i-s a plan view showing my invention bolted to the left side frame of a motor vehicle chassis;

Figure 2 is a vertical section on the line 2-2 of Figure 1, showing the actuator pedal at its upper limit, with the pistons in both the primary and secondary cylinders, at their inactive positions; i

Figure 3 is a view similar to Figure 2 but showing the actuator pedal partly depressed, and both pistons advanced to create quick volume, and showing the secondary piston locked against further travel, While the piston of the primary cylinder of smaller diameter continues its motion to createhigh pressure; Y

Figure 4 is a view similar to Figures 2 and 3, showing the actuator pedal further depressed, and showing small increased displacement in the primary cylinder, while the piston in the secondary cylinder remains stationary and is held against retrograde motion; and

Figure 5 is a diagrammatic application of a specic form of pressure actuator to four wheel brakes of a motor vehicle, the pressure actuator being in the inatcive position, as in Figure 2.

Referring now tothe drawings, numeral 2 represents the side frame of the chassis of a motor vehicle to which is secured the frame member 3, or support for mounting the device herein. The member 3 has a bracket extension 4 in which are provided bearings 5 and 6 for the rock shaft 1. A pedal or actuator 8 is keyed to the rockshaft 1 as at 9. A bell-crank Ill is also keyed to the rockshaft 'I at II.

When the invention is used for motor vehicles, there is provided the usual clutch pedal I2 with a hub I3 which pivots freely on the shaft 'I. Other pedals may be mounted on this shaft. To the frame 3 is secured the pressure cylinder casing I4. The cylinder casing I4 has a bore I5 dening the diameter of the primary cylinderI and in said bore is a piston I6 4provided with suitable'packing Il. A springk I8 is adapted to constantly press the piston I6 against the actu- -ator rod I9, which rod enters a conical socket in the end of the piston. The actuator rod I9 vao is provided with an extension connected as at 2| to one arm of the bell crank I0. The usual bellows or boot 22 protects the cylinder from dirt and other foreign material,` and this boot is clamped at its outer end for motion with the rods I9 and 20.

A fluid reservoir 23 is provided with a filling cap 24. A vent 25 permits the iiuid to `enter the cylinder I5, but return or back flow is prevented by the piston as it advances from its position in Figure 2 to that of Figure 3. A passage 26 connects the primary cylinder I5 with the secondary cylinder 21, which latter cylinderhas a piston M28 having suitable packing 29.

A spring 30 bears continuously against the piston 28 to normally keep it in the inactive position shown in Figure 2. The piston 28 hasa socket receiving an actuator rod 30' which rod is providedy with an extension 3I pivotally or hingediy connected to one arm 32 of a bell-crank member 33 as at 34. The bell-crank member 33 is pivoted on a stud 35 preferably provided with antifrictionneedle bearings 36. The stud 35 is secured to the frame member 3 as at 31. The member 33 is provided with an arm 38 having a roller 39 operating in a slot or fork 40 of the bell-crank- II).

The bell-crank I0 is provided with an exten-J resting the forward motion of the piston 28 at the proper time and in proper relation to the motion of piston IS.

A` suitable bellows boot is provided to keep dirt or other foreign substance out of the cylinder 21. `The cylinder 21 is provided with a drain plug 46 and with outlet plugs 41 having outlets 5I and 52. -A tube or conduit 48 may be connected to the outlet plug 41 and by means of suitable connections with the brake shoe cylinders 49 which actuate the brake shoes 50.

In the operation, pressure on the pedal actuator 8, Figure 2, advances both the piston I 6, which is of small diameter, and the piston 28, which is of much larger diameter. The fluid nf the small piston I6 iiows through the passage 26 into the cylinder 21A and the displacement of fluid by both pistons I6 and 28 occurs, the outflow beingthrough the outlet plug 41 to the single pressure line 48. The size of the cylinder 21 and the piston 28 plus the length of the stroke is so calculated as to provide for just enough displacement in relation with the smaller cylinder I5 and piston I6 as will cause it to come to rest as shown in Figure 3 approximately just after all of the slack has been taken up in the system, and when the brakes are ready to be applied by pressing the brake shoes against the brake drums. y

The toggle joint with its related parts so act that the piston 28 is held at the position of Figure 3 while the piston I6 continues to advance, the entire thrust being sustained by the stud 35 so as not to cause increased friction against the bearings of the pedal actuator 8. The arcuate surface 42 of the arm I0 'continues to act on roll.-

er 39 to maintain the arm 38 and related parts in the positions shown in Figures 3 and 4.

Since no great additional motion of the pedal actuator is necessary after the 'slack in the system has been taken care of by the action of the two pistons I6 and 28, the cylinder I5 and piston I6 can be greatly reduced in size over that heretofore required and yet be capable of creating very high uid pressure for urging the brake shoes against the brake drums, without much muscular exertion on the pedal actuator. The construction permits mounting of the whole unit rigidly in one casting member 3, and enables one to obtain maximum of eiciency, with minimum of size. The illustrated device is particularly adapted for 1% to 3 ton trucks, light buses and heavy motor cars.

'Ihe outlet 52 may be connected to operate hydraulic brakes on trailers and may also be successfully used in connection with vacuum power boosters or any other auxiliary power in addition to the pedal actuator.

It will be understood that it is not necessary to havey the pistons operate simultaneously. One piston could operate first and at the end of its stroke another piston could start operating. For example, the large piston could operate first and then the small piston. There is therefore no intention to limit the invention entirely to simultaneous operation of the pistons.

I claim as my invention:

1. A manually operated fluid pressure actuator for hydraulic brakes comprising fluid displacing cylinders, a'piston for each cylinder, and means for operating the pistons for limiting the displacement action of one, while continuing displacement action o`f the other, said means including a rock shaft having a bell crank lever thereon, a thrust member by which one arm of the bell crank operates one of the cylinders, and

advance of one of the pistons while continuing the advance of the other, including a break-joint thrust connection for one of the pistons, a thrust connection for the other piston, a rock lever having one portion operating said break-joint thrust connection to bring the joint from broken-joint position to non-broken-joint position, thereby to start and stop displacement action oi one o! said pistons, the other arm of said lever acting at the same time to operate thrust connection of the other piston.

3. In a device of the class described, a bell crank lever, one arm ofv which has a surface which is concentric with the axis of rotation of the lever, said arm having a recess which intersects said surfaee, a pair of cylinders having pistons, means for operating one of the pistons including a device having a. break joint and having a member which is operated upon by said recess to cause the joint to`assume non-broken condition andthereby arrest motion of the corresponding piston, and which engages said concentric surface when the joint is in non-broken crankA lever for simulttaneously operating the other piston, whereby both pistons are initially simultaneously operated and then operation of one piston is arrested while operation of the other is continued.

4. In a device of the class described, a pair of members to be moved, a rst thrust element for moving one of the members and a second'breakjoint thrust element for moving the other member, and means including a rock lever having two arms, each operating' one of said thrust elements, so that as the rst member is moved, the break joint is moved to non-break position, thereby limiting the movement of said second member while continuing the movement of said iirst member.

5. In a device of the class described, a pair of cylinders each having a piston therein, means for advancing. the pistons including a rock shaft having a bell crank lever thereon, means by which one arm advances one of the pistons, a break-joint thrust element comprising first and second hinged together parts normally out of alinement, the rst part engaging said other piston and the second part being rotatably mounted, and means respectively on the second part and on the other arm of said bell crank lever by which said second part is rotated to bring the parts intoalinement to advance the second piston when the shaft is rotated to advance the rst, and whereby after the partsA in the same direction.

6. A manually operated fluid pressure producer for operating brake cylinders, comprising a pair of cylinders and pistons of different displacements and having a common outlet in communication with the brake cylinders, a pedal pivoted on a support, operative connections between said pedal and the smaller piston for developing pressure in the cylinder, toggle means pivoted on a different support and connected with the larger piston for developing pressure in the larger cylinder and a mechanical connection between said pedal and said toggle means for straightening out the toggle and thereby moving the larger piston on its pressure development stroke.

- EDWIN G. STAUDE. 

